THIS IS WHAT I'M TALKING ABOUT! Half the games here have some point system but it's the online leaderboards, that make it the good game with points great!
If this game had one level, this would be great, but you made three. I think that the green one is the best balanced. The purple one has huge enemies, that take too much space (then again, that the theme, right?), and the red one is a bit too hard (didn't finish, always killed with last five guys left).
Presentation is perfect. You can always see what's going on, who is alive, and who is not. Well... almost. Fire level is too pretty. The effect looks awesome, but is't a bit distracting, and in a game where reflex and precision count this is the difference between being on a leaderboard and not :)
Audio is perfect. You can focus on fighting and dodging, and still you know when new guys appear!
As for the theme, you landed it- the space is limited, and it only becomes more limited. You can clear it a bit, but it costs time, so it's a bit of risk-reward situation.
There is one thing I would change, and it's not about the game. The thumbnail. When I clicked it, I was CERTAIN it was a puzzle game about letters. Seriously- delete it, take the screenshot from the fire level, and use it instead.
One of the best games of the jam!